Polishing wax emulsion and method of producing it



United States latefit ce POLISHING WAX EMULSION AND METHOD OF PRODUCINGIT Ralph K. Iler, Wilmington, Del assignor' to E. I. du Pont de Nemoursand Company, Wilmington, Del., a corporation of Delaware No Drawing.Application December 3, 1951, Serial No. 259,689

2 Claims. (Cl. 106-10) This invention relates to novel wax compositionsand more particularly to compositions which comprise aqueous dispersionsof a wax and colloidal silica.

This application is a continuation-in-part of my United Statesapplication Serial No. 775,375, filed September 20, 1947, for ChemicalCompositions which has a continuation-in-part of my United Statesapplication Serial No. 699,087, filed September 24, 1946, for ChemicalCompositions.

Wax coatings are commonly applied to the surfaces of furniture,automobiles, and wood, asphalt tile, and linoleum floors for the purposeof imparting a pleasing, lustrous appearance and a protective filmagainst dirt and moisture. Suspensions of such waxes as carnauba,montan, candelilla, beeswax and paraffin have been used for this purposeand have been applied in such forms as aqueous dispersions andsolvent-containing pastes. Some of these compositions are of theself-polishing type, that is, they are applied as a suspension of wax ina carrier such as water and dry to a polished appearance without furtherrubbing.

Conventional'wax compositions ordinarily include certain extenders ormodifiers in the wax dispersions. These may comprise wax-soluble orwater-dispersible natural or synthetic resins such as, for example,manila gum or polymeric alkyd-modified esters of rosin. U These may beused in greater or lesser amount, dependingupon the specific type ofcoating composition which is desired. The addition of such resindecreases the cost and often gives improved levelling or spreadingproperties to the wax dispersion.

Many wax polishes which have been proposed give coatings of pleasingappearance but which unfortunately are lacking in resistance toslipping. Such formulations,

when applied to linoleum floors, for instance, give coatings which arenot entirely safe to walk upon, in that leather shoe soles slide quiteeasily upon them. Similarly, rugs placed upon floors waxed with suchmaterials slide readily when stepped upon and constantly are a hazard.

Efforts have been made to correct this lack of slipresistance byincluding other materials, for example, ground feldspar, in the waxformulation. Such inclusions, however, often result in an impairment ofthe luster and pleasing appearance of the wax-coated surface.

Now according to the present invention it has been found that byincluding colloidal silica in aqueous wax 2,726,961 Patented Dec. 13,1955 dispersions novel compositions are produced. The silica improvesthe characteristics of the dispersions. In the case of compositionscontaining comparatively large amounts of wax as compared to modifiers,the silica will increase the slip-resistance of films produced usingsuch dispersions. In compositions of the invention the silica has thefurther effect of increasing the hardness of the film, and it is furtherto be noted that wax dispersions containing compar'ativelysmall amountsof wax and comparatively large quantities of resins are improved as totheir ability to produce coatings which are not objectionably tacky. Thebenefits obtained using silica are gained without objectionableimpairment of the luster, of films produced from wax dispersions.

The colloidal silica used accordingto the present inven= tion isprepared according to processes described in an application of Joseph M.Rule, United States Serial No. 183,902, filed September 8, 1950, forChemical Processes and Compositions. In general, it may be noted of suchcompositions that the colloidal silica is added as a sol containingamorphous silica particles which are dense, non-agglomerated, spherical,and have an average diameter of 10 to millimicrons, the silica solhaving a silicazalkali metal oxide mol ratio of from 130:1 to 500:1, arelative viscosity of from 1.15 to 1.55 as measured at 10% SiO2 and pH10, and a specific conductance, as measured at 10% SiOz and 28 C., ofless than where R is the silicazalkali metal oxide mole ratio.

THE WAX DISPERSIONS The invention has application to such aqueous waxdispersions as the relatively dilute waxes of the self-polishing type,the more concentrated water-containing wax pastes, and other suchcompositions in which wax is dispersed in an aqueous medium.

The term Wax as used herein will be understood to include not only thenaturally occurring materials composed largely of fatty acid esters ofhigh molecular weight monohydric alcohols, such as carnauba, candelilla,and beeswax but also other organic, Water-insoluble materials which havethe physical character of waxes. This is in accord with general usage inthe art, as is illustrated in an article entitled Waxes in industry-J"by A. H. Wood- ,head, in Paint Manufacture, vol. 17, page 40 (1947).

It has been the practice in recent years to include in the term waxthose substances which bear some physical resemblance to any of thenatural waxes, including paraffins and ozokerites. This definition ismore useful since the inception of' a large range of synthetic productsof ally complex, which ,is of amorphous or microcrystalline 3. structureand usually lacking excessive tack at normal temperature, and whichmelts fairly sharply to give a (usually) mobile liquid at a temperaturebut little higher than its normal melting-point. This definition largelyexcludes resins and the common simpler crystalloidal chemicals.

While this definition largely excludes resins it will be noted thatthere is a group of high molecular weight polymeric materials commonlycalled synthetic waxes which have wax-like physical properties and henceare included within the definition. It has been found that emulsions or,more properly, suspensions of such high molecular weight polymericwaxes, in combination with colloidal silica, particularlysodium-stabilized colloidal silica, provide improved water-proofing andpolishing compositions in accordance with this invention.

The waxes thus fall into three general categories, namely, the esterwaxes mentioned above which are usually naturally-occurring either asplant exudations or animal excreta, the hydrocarbon waxes, oftenreferred to as mineral waxes, including montan, ozokerite, ceresin, andparaflin, microcrystalline waxes, oxidized petroleum waxes, andsynthetic polymeric waxes, including condensation products of hardenedcastor oil or octadecanediol with boric acid, monobasic carboxylic acidesters of perhydrogenated novolac, polyethylene adipate, wax-liketelomerization products prepared by methods shown in United Statespatent of Hansford and Joyce, No. 2,440,800, issued May 4, 1948, such asthose of ethylene and dichloroacetic acid, and the correspondingethylene telomerization products with bromacetic acid.

The naturally-occurring waxes such as carnauba, candelilla, and many ofthe hydrocarbon waxes are Well known and characterized in the art. (See,for example, The Chemistry and Technology of Waxes, A. H. Warth,Reinhold Publishing Corp., 1947). The oxidized petroleum waxes and themicrocrystalline petroleum waxes are commercial materials which arereferred to by their trade names throughout the examples and the rest ofthe present disclosure as a matter of convenience. However, thesematerials are further characterized by means of the chemical andphysical properties given in the tabulation below. The microcrystallinewaxes are defined in the Chemistry and Technology of Waxes, at page 240,as follows: A solid hydrocarbon mixture, of molecular weight averaginghigher than paralfin wax, possessing plastic properties, separatedentirely from the part of crude petroleum commonly designated as heavylubricating and cylinder oil stocks, and having a minimum kinematicviscosity of 5.75 centistokes at 210 F. and a maximum penetration of 60at 77 F., determined by A. S. T. M method D5.-25. The oxidizedhydrocarbon waxes are prepared by the controlled catalytic oxidation ofhydrocarbons to produce the desired number of earboxyl, carbonyl, orester groups as determined by measurement of such properties as the acidnumber, saponification number, and the like. A number of these materialsare characterized in the following tabulation:

Characterization of commercial petroleum waxes 1 Determined by A. S. T.M. method D-12'i-3tl. 2 Determined by the conventional method. 3Determined by A. S. T. M. method D-5-25.

The waxes described above when made into aqueous dispersions may bethere modified and extended by the incorporation of resins. The waxdispersions, including the various polishing compositions conventionallyused in the art, are conventionally modified in such manners. The resinsmay be waxrsoluble or miscible, in which case they may be blended intothe molten wax. Other resins may be water-dispersible, and their aqueousdispersions may :be. incorporated into the wax emulsions. The commonlyused natural, resins, such as shellac and manila gum, are well known.and characterized in the art. A, number of Synthetic commercialmaterials are referred to by their trade, names throughout thisdisclosure and the examples. as. a matter of convenience. Thesematerials .are characterized .by means of the physical and chemicalproperties given in the tabulations below. Where the chemical structureof the synthetic polymeric material is known, this information is alsogiven for a complete characterization. The proportions of these resinswhich may be used in the compositions of this invention and the'methodof'incorporating them is described hereinafter:

Characterization of commercial water dispersible resins Index of MeltingSaponi- Specific Acid Ream Gravity 2 2 553 a a 6 33a; 2 Number 1Chem-cal Typo Shellac 5 45-65 Natural mixture of polyhydroxy acids andtheir esters. Manila 5 -150 Neturinal ,copal. type alcohol soluble res130-138 A modified maleic type. Amberol 750 -105-115 A fortified ammoniasoluble mitleic ester of rosin.

Dulez 15546 1.17 1. 542 4 :1:3 130. 55

1 Determined by ASTM method D-127-30.

a Determined by the mercury method.

4 Determined by the capillary tube method. 5 Characterized inProtective+Decorative Coatings, vol. 1. J. ,J. Matiello, John Wiley 6:Sons, Inc. New York,

New York, 1946.

6 Characterized in Resinews vol. XV, published by 17.8. IndustrialChemical-.00., copyright 1947. 7 Characterized in Amberol 750 in WaxEmulsions, Product Bulletin, .form 203, published by Rohm 5; Haas 00.,

J une-1950.

8 1 6 aharaeterized as Durez 15325 ground to 20 mesh in Technical DataBulletin of U. Industrial Chemical Co., dated Product Specificationslisted on container.

sateen Index of Melting Saponi- Type Specific Acid Resin Refrac- Pointflcation Chemical Type Chemical Gravity 2 tion 3 C. Number 1 Number 2Formula liewisol 28 1. 138 143 i 36 A inaleic alkyd-modified ester 5 A orosin. "Piccolyte 8-85 0. 98-1. 1 85 0-4 0-4 A polyterpene predominantlyB beta pinene. Durez 219 1. 085 13 135 50-60 A terpene phenolic"Pentalyn A 1. 08 5 110 14 A pentaerythritol ester of rosin. -11 CPentalyn C 7 1.09 15 Anfiodiiied pentaerythritol ester 0 rosin.

! Determined by A. S. T. M. method D-127-30. 2 Determined by theconventional method at 25 C. a Softening point, determined by Herculesdrop method.

4 Molecular weight averages about 650. Ash less than 0.12 8.Characterized in Piccolyte the Versatile Resin, published byPennsylvania Industrial Ch 5 Characterized in supplement to copyrightJanuary 1944. Viscosity=E, Gardner-Holdt, at 25C. on 60% 1 Characterizedin Hercules Synthetic Resins, 5 Modern Same as 8, p. 1038. Same as 8, p.1041.

em. Corp. Copyright 19 Hercules Chemist, N o: 13, O. A. Pickett,published by Hercules Powder 00.,

solution (by weight) in toluene. published by Hercules Powder 00.,copyright 1947. Plastlw Encyclopedia. Plastics Catalogue Corp, New York,N. Y., 1950, p. 1041.

11 Pentalyn and Pentalyn G, esters of Pentaerythritol and Resin,published by Hercules Powder 00., form 917 Durez Protective CoatingResins in Emulsion-Paste and Liquid Waxes, published by Durez Plasticsand Chemicals. Inc.

13 Determined by capillary tube method.

The amount of a wax used in an aqueous dispersion of this invention maybe widely varied depending upon the particular use for which thecomposition is intended. When the composition is in paste form, as inthe rubto-polish type, the proportion of total solids, exclusive ofsilica, may be from 20 to 40% by weight of the total composition, andmost of this 20 to 40% will be wax. On the other hand, in the aqueouswax dispersions of the selfpolishing type, in which the colloidal silicais particularly effective, the proportion of total solids, exclusive ofsilica, may be from about 10 to 15% by weight of the total composition,and this 10 to 15% may include wax, emulsifier, and wax-soluble andwater-dispersible resins.

More specifically, thewax dispersions to which colloidal silica sol isadded according to this invention preferably will. contain, on the basisof total solids exclusive of silica, about from 15 to 70% of wax, 0 to25% of waxsoluble resin, 3 to 16% of emulsifier, and 0 to ofwater-dispersible resins, all percentages being by Weight. It will beevident, of course, that maximum proportions of each of theseingredients will not be simultaneously present and that the relativeproportions will be selected, as shown in the specific examples, to givethe particular properties desired in each instance. Liquids which arenot volatile at the temperatures used in making the compositions arecounted as solids, whereas volatile liquids are not included as solids.

CHARACTERIZATIONS Wax dispersions as above described are modifiedaccording to the present invention by the addition thereto of sols ofcolloidal silica of a type more specifically to be describedhereinafter. Before proceeding to a description of the silica sols usedand the method of their application, the following description is firstgiven of characterizations which are useful both in considering theproperties of wax films obtained and in examining silica sols. Thedescriptions hereinafter of the silica sols and of their use will bemore understandable in the light of these descriptions ofcharacterization methods.

Particle size measurement by the electron microscope The size of thesilica particles and the fact as to whether or not they arenon-agglomerated, that is, substantially discrete, can be directlyobserved if the silica is spread out in an extremely thin layer andexamined with the electron microscope. Since the limit of resolution ofthe electron microscope is well below the 10 millimicron limit of theparticles, there is no difiiculty in ascertaining whether particles ofthe desired size are present. By examining the silhouette of theparticles it is possible to measure the particle diameter in those caseswhere the particles are lying in such a way as to present more than asemicircle of cross section. Where less than a semicircle of crosssection of a particle can be observed due to the fact that it isobscured by other particles, the particle is not measured. However, bycounting and measuring a large number (several hundred) of particleswhich are lying in such positions as to present at least a semi-- circleof silhouette, the arithmetic mean particle diameter,

average diameter, ds, can be determined.

ameter, a specific surface area, Sc, can be calculated. This is thespecific surface area particles, having an entirely exposed smoothsurface.

In counting the particles, they are grouped according:

which the ultimate units. would have if they were non-agglomerated,discrete, dense:

to diameter, as measured in millimicrons; each group .consists ofparticles lying within a five millimicron range, for example, 10-15millimicrons, -20 millimicrons, 25 millimicrons, etc. The surface areaof the particles within each group is calculated from the averagediameter of the group and the number of particles within the group. Thetotal surface area of all the counted particles may then be calculatedby summation of the areas in each group. The specific surface area isthis total surface area, divided by the total mass of the particlescounted, the latter being determined by summation, using the knowndensity of the silica.

In carrying out this calculation, it is convenient to calculate first asurface area average diameter, ds, which would be the diameter of .aspherical unit having the same specific surface area as that of thetotal collection of counted units.

This may be expressed mathematically, as follows:

Enid? i=1 ex 10 2720 densi0y X d., d, The arithmetic mean particlediameter is simply the number average particle diameter, dn, which isdetermined from the formula where m and d1 are defined as before and nis the total number of particles, counted.

in determining the size of silica particles by the electron microscope,it is necessary to avoid changes such as agglomeration or coalescence ofthe particles which may occur'in drying the sols. This is minimized bydiluting the sol and allowing the water to evaporate at roomtemperature. The sample may be diluted to a concentration of from about0.25 to 0.01% of SiOz, but in general the maximum dilution will be usedwhich permits retention of a sufiicient number of' particles in thefield to permit counting of the particles as described above.

The particle counts are made from electron micrographs taken at 5,000diameters magnification enlarged to 25,000 diameters by conventionalphotographic printing techniques and finally projected on a screen to atotal magnification of about 250,000 diameters. Methods of mounting thesamples, and counting and measuring the particles are described by J. H.L. Watson in an article entitled Particle size determinations withelectron microscopes in Analytical Chemistry, volume 20, pages 576-584.for June 1948. The method of calculating particle size distribution isdescribed in an article by L. R. Sperberg and H. M. Barton in RubberAge, volume 63, pages 45-51 for April 1948.

Surface area determination by nitrogen adsorption The density of thesilica particles may be determined by comparing their surface areas ascalculated from electron micrographs as described above with the surfaceareas as determined bynitrogen adsorption. The method used for measuringspecific surface areas by low temperature nitrogen adsorption isdescribed in A new method for measuring'the surface areas of finelydivided materials i3 and for determining ,the sizetof particles by P. H.Emmett in Symposium .on New .Methods for .Particle .Size Determinationin .the Sub-Sieve Range, p. 95, published by The American Society ,for'Testing Materials, March 4, 1941. "l he' value of 16.2 for the areacovered by one surface adsorbed nitrogen molecule was used in calculat-'ing thespecific' surface areas.

When evaporating the sols .to dryness for nitrogen adsorptiondeterminations on the particles therein, the .sols should be adjusted toa pI-Iof about 3. to 4., and dried at room temperature and then at C. Ifthe S01 is evaporated in the basic pH range, the specific surface areaas determined by nitrogen adsorption will besignificantly less than thesol is'evaporated in :the acidic pH range of .3-4. This decrease .inspecific surface area upon evaporation in the basic region appears to bedue to a coalescence of the silica particles.

It the specific surface area as determined by nitrogen adsorption is notsubstantially greater, for example, not more than 25% greater, than thespecific surface area as calculated from electron micrographs theparticles are dense and the sol is suitable for use in the process ofthis invention. 'If the silica particles are porous they will bepenetrated by nitrogen and the nitrogen adsorption will be relativelyhigh, and consequently the specific surface area by nitrogen adsorptionwill also be highmuch higher than would be expected on the basis of thedirect observation of the particles by means of the electron microscope.On the other hand, if the specific surface area by nitrogen adsorptionis not substantially greater than that calculated from electronmicrographs, the particles are substantially smooth, discrete,non-porous spheres. This confirms direct observations as made with theelectron microscope.

Measurement of relative viscosity Relative viscosity is determined asdescribed in Bechtold and Snyder United States Patent 2,574,902, atcolumn 6, lines 41 to 66.

Measurement of specific conductance The specific conductance of thesilica sols used in this invention may be determined in accordance withconventional practices, such as those described by Glasstone, Textbookof Physical Chemistry, at page 874 et seq. The specific conductance ismeasured at 28 C. on a sol containing 10% by weight of silica expressedas SiOz. Measurement of turbidity and of molecular weight by lightscattering See United States Patent 2,574,902, columns 4 to 6.

Chemical analysis Standard analytical techniques are used throughoutwith the following limitation.

Determination of titratable alkalinity: In order to determine theSiO2:M2O.ratio, it is necessary to analyze the solution for silica andtitratable alkalinity. The latter is determined by titrating the solwith HCl to a pH of 4.5 using a glass electrode pH- meter.

Determination of properties of wax dispersions The characteristicsofmodified aqueous wax dispersions containing colloidal silica sols.according to the invention can be measured by examination both of themodified wax dispersions and the films cast therefrom. As indicatedbelow, many of'these tests were run in conformity with theSpecifications for Floor Wax; Water-Emulsions, No. 784a, dated March 27,1950, superseding in turn No.

784 dated June 28, 1948, andthe Proposed Revision of Specification 784,November 1949 of the General Services Administration of theFederal-Government.

The temperature stability of the modified wax dispersion was determinedby heating a sample of the dispersion to 52 C. for 1 week or more andobserving visually any significant changes in the emulsion such asgelation, phase-separation,precipitation, or the like. Thelowtemperature stability was determined by subjecting the modified waxdispersion to 3 freeze-thaw cycles and examining the properties forsignificant changes. In some cases the properties of films cast from thedispersions were measured after subjection to the high or lowtemperature tests and were compared with the properties of thedispersions stored at room temperature.

The conventional properties of films prepared from the modified waxdispersions were measured according to the procedures below. The filmswere prepared by using gauze pads soaked with the modified waxdispersion and applying two coats of the dispersion, 24 hours apart, tobrown battleship linoleum. i

Leveling prperties.-The appearance of the film was examined with regardto undesirable lap marks, puddling, and highlights. The qualitativerating of E, for Excellent, was assigned to films showing no streaks orhighlights; the rating G, for Good, was assigned to films exhibitingsome lap marks but no puddling; the rating P, for Poor, was assigned tofilms showing bad puddling.

Gloss.The gloss is measured by means of the Gardner laboratory 60 glossmeter as described in the abovementioned Federal specifications, exceptthat the films are prepared on linoleum as described above. A glossreading above about is considered good whereas a gloss reading aboveabout is considered excellent.

Water resistance.-This property was measured on the coated panel afterthe second coat had dried for twentyfour hours. One-half to one cc. ofdistilled water was placed on the wax film and allowed to stand for onehour after which it was removed. The spot was observed after drying. Ifno mark was visible the film was rated E for Excellent; if the filmshowed a very slight haziness while remaining glossy, it was rated G forGood; if the film remained intact but showed a white or gray spot it wasrated F for Fair; if a very white spot resulted and the film had atendency to lift it was rated P for Poor. The spots were bufied slightlywith a cotton pad and observed again to further demonstrate thedifierences.

Dynamic coefiicient of fricti0n.--The slip-resistance of the wax filmsmodified with colloidal silica is measured in terms of the dynamiccoefiicient of friction as described in Section 4.2.20 of the ProposedRevision of Specification 784 as listed above. The test involves the useof a Sigler pendulum-impact type slipperiness tester. This instrumentwas originally described in the Journal of Research of the NationalBureau of Standards, volume 40, page 339, 1948, by Sigler, Geib, andBoone. The instrument readings will, of course, vary with the type ofsurface to which the wax dispersion is applied aswell as with theconstituents of the dispersion. On battleship linoleum a reading aboveabout 0.42 is regarded as an indication of excellent slip resistance andthe effect is readily perceptible upon attempting to slide the soles ofones shoes over such a surface. A reading of 0.40 to 0.42 is indicativeof good slip-resistance. Readings below about 0.40-are indicative offair to poor slip-resistance.

In addition to the tests on brown linoleum the clarity and gloss of thefilms are measured on black glass as described in theabove-mentioned-Federal specification. The leveling properties, gloss,wet abrasion resistance, and removability are also determined on blackrubber tile according to the above-mentioned Federal specification No.7845:. Thewet abrasion resistance is given a qualitative rating of from0-4 according to the following scheme: No attack is rated zero; theappearance of less than 6 tiny flecks or whitened spots is rated 1; morethan 6 tiny flecks but no definite film failure is rated 2;.if thewhitened area consists of more than 6flecks but is less than 1 sq. in.in area the film is rated 3; if the whitened area is greater than 1 sq.in. and there is definite film failure, the film is rated 4.

THE COLLOIDAL SILICA The term colloidal silica as used in describingthis invention refers to silica in the form of particles of colloidaldimensions, that is, particles having an average size not exceedingabout 150 millimicrons nor less than about 1 millirnicron. It isparticularly preferred to;use colloidal silica having an averageultimate particle size less than about 30 millimicrons, that is, 0.03microns. By ultimate particle size is meant the average size of particlepresent when the solution is diluted to about 0.1% of SiOz with waterand dried in a verythin layer deposit.

The silica particles will not necessarily be presentas anhydrous silicondioxide but rather, may be in a hydrated form associated with variousproportions of water. Thus, partially dehydrated silicic acid would comewithin the term silica as herein used.

In the processes and products of this invention, the colloidal silicasols used are comparativelytree from impurities. A colloidal silica solextremely low in elec trolyte may be prepared by treating a silica solcon taining dense, spherical, substantially non-agglomerated silicaparticles, such as that produced by the processes of Bechtold and SnyderUnited States Patent 2,574,902, dated November 13, 1951, with cationandanion-exchangers alternately until the specific conductance as measuredat 10% SiOz and 28 C. is less than 4X10- mho/cm. To this sol there isadded back enough alkali metal hydroxide to adjust the silica: alkalimetal oxide mol ratio to from :1 to 500:1. Sols thus prepared aredescribed and claimed in U. S. patent application of Joseph M. Rule,Serial No. 183,902 filed September 8, 1950.

Similar products may also be made by deionizing a silica sol of smallparticles such as that obtained by ion-exchange to attain a starting solof a purity as above described. A portion of such a sol can then beheated to a temperature above 60 C. while further quantities of the samematerial are added slowly over a comparatively long period of time toetfect particle growth. In doing this the alkali should be adjusted tothe range above indicated so that the ratio of SiOzzNazO is within therange 130:1 to 500:1. Such processes are described in United Statespatent application of Joseph M. Rule, Serial No. 183,901, filedSeptember 8, 1950, for Chemical Processes.

The silica mols as thus propared which are added to a wax emulsionaccording to the invention have a silica: alkali metal oxide mol ratioof from 130:1 to 500:1, a relative viscosity of from 1.15 to 1.55 asmeasured at 10% SiOz and pH 10, and a specific conductance, as measuredat 10% SiOz and 28 C., of less than zg +s0 X 10- mho/cm.

where R is the silicazalkali metal oxide mole ratio, and containingamorphous silica in the form of dense, non agglomerated, sphericalparticles having an average particle diameter of 10 to 130 millimicrons.

It is to be noted that sols as thus prepared can contain larerquantities of silica than can be presented in stable silica solsprepared in the presence of electrolytes. In other words, solscontaining electrolytes or sols in which the particles are not dense andunagglomerated cannot practically be concentrated to SiOz contentshigher than, say, 15 to 18% unless products of the type described byBechtold and Snyder are used, in which case stable sols up to, say, 35%can be made. Sols of the type used in the present invention can be madein concentrations up to, say, about 50% SiOz.

While the proportion of silica used in aqueous dispersions of theinvention may vary widely depending upon the specific composition to bemodified, it may be observed that it is usually preferable to use fromabout 10 to 50% of SiOz based upon the total solid content of the waxdispersion or emulsion to be modified. The solid content mentionedincludes the wax emulsifier. resins, and other modifying agents.

It should be observed in connection with the contents of silica in thecompositions thatfor purposes of convenience in description it willoften be noted hereinafter theta wax emulsion polishing compositioncontains an aqueous silica solof the characteristics herein described.It will be understood that the sol is added to the emulsion and ittherefore contains it in that sense. It is not to be understood that thesol is necessarily unmodified by materials which may be present in theemulsion.

MAKING THE DISPERSEON The aqueous wax dispersions of this invention maybe prepared according to methods with which the art is familiar and willordinarily contain a dispersing agent such as mono-, di-, ortriethanolamine oleate or stearate, Z-amino, Z-methyl, l-propanol,sodium or potassium soaps, morphdline oleate, or monoethylamine oleate.In the examples given below the methods of preparation referred to byRoman numerals are as follows:

Method I This is perhaps the simplest and most easily controlled method,but its use is limited to the more easily dispersed waxes, such ascarnauba, montan, candelilla, etc. .The. wax to be dispersed is placedin the beaker which is immersed in the steam bath (to prevent wax cakingon the sides) and melted. The oleic acid can be melted along with thewax, can be added when half the wax is melted or after all the wax ismelted, but in the present use the oleic acid (or stearic acid) wasadded when half .the wax was melted. Meanwhile on a separate hot platethe correct amount of water is brought to the boiling point. To themelted wax is added the triethanolamine (morpholine, etc.) and stirredthoroughly. To this is then added the boiling water and the mixture isvigorously stirred to form a smooth suspension of wax in water. Whenpotassium hydroxide and/or borax are called for in the formulation theycan be added to the water before pouring into the wax or in the case ofthe dissolvedflpotassium hydroxide, it can be added immediately afterthe triethanolamine is added. in the case of the test suspensions thecolloidal silica is added to the water before the latter is added to themelted wax.

Method 11 (C. H. Bennett, Commercial Waxes, pages 469 to 470) III-thismethod, the wax or oil is emulsified by means of .a water solution ofthe soap which is made from triethanolamine and stearic acid (or oleicacid). The water .is measured out into a container which can be heated.The triethanolamine is then added and stirred into this and then thestearic acid is added. On being heated, the acid gradually melts and canbe stirred into the water to give a smooth soap solution, and thetemperature is raised to just below the boiling point. The wax is nowmelted in a separate container and its temperature brought to 85-95 C.This is then added to the water solution and the whole solution at oncestirred vigorously to obtain a good emulsion. Stirring is then continuedgently until the product has cooled.

It. should be noted that when the water is added to the wax care shouldbe exercised since a great amount of foaming is produced and the wax isdispersed with almost explosive violence. In the case of the testmixtures the colloidal silica was added to the water just before it waspoured into the wax.

Method 111 This was a modification of Method II. The potassiumhydroxide, triethanolamine, and oleic acid were added to the water whichhad previously been heated to 90 C. with rapid agitation. In themeantime the wax was brought to a temperature of 140150 C. The wax wasadded to the aqueous solution slowly with rapid agitation. After all thewax had been added, the resulting suspensionwas stirred for fiveminutes. The suspension was then cooled for five minutes with noagitation and thenithe. beaker was floated in a large pail of wateruntil cooled; While cooling, the suspension was stirred occa- '12sionally to break up a thin crust which formed on the surface. Whencolloidal silica solution was present it was added to the water at thestart of the preparation.

Method IV This method was particularly effective for dispersingsynthetic waxes. The dispersing agent and wax were placed inan aluminumbeaker, melted together, and the hot melt stirred with a drink mixer.This mixture was then heated to 140150 C. on a hot plate. In themeantime the water was brought to a temperature of C. and 30% of thewater was slowly added to the hot wax solution with rapid stirring. Theresulting emulsion was then slowly added to the remaining water at 90 C.This procedure was adopted because it gave extremely finely divided,stable dispersions of carnauba wax which dried to continuous, lustrousfilms.

Method V A. The following method is a slow inversion method applicableto aqueous wax dispersions containing modifying resins. The wax isheated to such a temperature as is necessary to obtain solution of theresins in the wax; this is about l20-150 C. The resins, usually inpowdered form, are stirred into the melt until dissolved. The melt isthen allowed to cool to a temperature of about 110-120 C. and the oleicacid is added. When the temperature has dropped to about -97" C. the m0rpholine is added very carefully and the mixture is stirred for 10minutes. If ammonia is used in the formulation it is diluted to about7%, warmed to 7075 C. and incorporated carefully into the melt at 95 C.with good stirring. Boiling water is then added with good stirring, tothe wax melt kept at 93-95 C. in order to produce an emulsion ofwater-in-oil. Ordinarily about 75-100 parts of the boiling water areadded per parts of wax plus resin to form a clear, viscous gel. Morewater is added gradually until the emulsion inverts to a non-viscousoilin-water emulsion. Then more water up to a total of, say, 400 partsis added. This is followed by the addition of parts of cool water (ZS-30C.); the emulsion is cooled with stirring to 30 C. and diluted to thedesired solids content which is usually about 12%.

The above parent wax and wax-soluble resin emulsion may be furthermodified by the addition of an aqueous dispersion of a modifying resin.For convenience the parent modified wax emulsion may be called A and themodifying aqueous resin dispersion may be called B. The ratio of theparent wax dispersion to the modifying resin dispersion may vary fromabout 3.5 :1 to 6.5:1 as parts by weight of dispersions of equal solidscontent. It is preferred to work with a solids content of about 12-l4%.It is understood, of course, that for certain uses it may be desirablenot to use any water dispersible modifying resin.

B. The preparation of a number of typical aqueous dispersions ofmodifying resins is given as follows:

MANILA LOBA C 100 parts powdered manila Loba C 36 parts 28% ammoniaWater, quantity sufiicient for 12% solids.

Three hundred parts of water are heated to 60 C., and 36 parts of 28%.ammonia added. To this mixture, kept at 60 C., is added, with stirring,a paste prepared from 100 parts of powdered resin and 100 parts water.When dispersion is complete (1-2 hours), the mixture is diluted to therequired solids concentration and filtered to give a clear dispersion.

AM'BEROL 750" 100 parts Amberol 7'50 (Rohm and Haas Co.) 25.6 parts 28%ammonia Water, quantity suflicient for 12% solids.

One hundred parts Amberol 750 are added to 700 parts of water with goodagitation over a 5-10 minute period. The ammonia is added, thetemperature is raised- 13 to 65 C., and stirring at this temperature iscontinued until dispersion is complete. Suflicient water is added togive the required solids concentration.

RESIN or-597" 100 parts or-597 resin (U. s. Industrial Chemicals, Inc.)

23 parts 28% ammonia Water, quantity suflicient for 12% solids.

One hundred parts X-597 resin are added to a solution of 23 parts of 28%ammonia and 300 parts of water. The mixture is stirred at roomtemperature until dispersion is complete (1-2 hours). It is then dilutedto the desired solids content and filtered to give a clear sol.

SHELLAC 100 parts bleached, dewaxed shellac 9.6 parts 28% ammonia Water,quantity sutficient for 12% solids.

Three hundred parts of water are heated to 60 C. and the ammonia isadded. The shellac is addedto the solution at 60 C., and stirred untildispersion is complete (about one-half hour). The dispersion is cooled,diluted to the required solids content, and filtered.

Alternatively, the shellac may be dispersed in the following manner:

100 parts bleached, dewaxed shellac 17 parts borax Water, quantitysuflicient for 12% solids.

Four hundred parts of water are heated to 60 C. and the borax isdissolved therein. The shellac is added to the solution at 60 C., andstirred until dispersion is complete (about one-half hour). Thedispersion is cooled, diluted to the required solids content, andfiltered.

It is preferred to dilute solutions A and B to the same solids content.The dispersions may then be mixed at room temperature with agitation.

C. The mixture of (A) and (B) is then further mixed with a sol ofcolloidal silica. Again, it is easiest to use the silica in the form ofa sol having a solids content equivalent to (A) and (B). For instance,if the solids content of (A) and (B) is 12%, then the silica sol shouldcontain 12% SiOz by weight. For convenience, this silica sol may bedesignated C. The ratio of the mixture A-l-B to the silica sol can varyfrom, say 1:1 to :1 as parts by weight of dispersions of equal solidscontent. In other words, if the dispersions are at equal solids content,then C "T 1 for most uses excellent properties are obtained with a ratioof from 1.5:1 to 3:1. More specifically, it is preferred that the ratioequal2: 1. If the dispersions are not at exactly the same solidscontent, then of course, the amounts of dispersions taken must beadjusted so that the ratio of the solids will be that indicated above.

DILUTE COLLOIDAL SILICA (12% $102 The colloidal silica sols, containingup to 50% silica,

may be diluted with water for use in the wax dispersions.

Morpholine orethyl amine may be added to improve such properties asfreeze-resistance. To avoid the formation of a flocculant precipitate ofsilica, it is best to add about two-thirds of the required water to theconcentrated sols before adding the amine, which is diluted with aboutone-third of the water required. The solutions are mixed thoroughly bystirring. Up 'to about 15% by weight of the amine based on the weight ofsilica in the sol may be added as disclosed in the copending UnitedStates patent application of F. I. Wolter, Serial No. 173,473, filedJuly 12, 1950. It may also be as little as 8% or less depending on theamount of excess amine used in preparing the wax emulsion.

Method VI A resin modified wax emulsion may also be prepared by a quickinversion method. In this procedure, the wax and wax-soluble resins aremelted as described in Method V, and the oleic acid, morpholineand'dilute ammonia are added as also described there. The water-in-oilemulsion is then inverted rapidly to an oil-in-water emulsion by therapid addition of 400 parts of boiling water with very vigorousagitation. Then 100 parts of cool water are stirred in, and the emulsionis cooled to 30 C. before dilution to 12% solids. The rapid inversionmay also be carried out by the reverse process, i. e., by adding themolten mixture of wax, resin, soap, and a small amount of Water rapidlyto 600 parts of boiling water with vigorous agitation. The resultingemulsion may then be cooled and diluted as described above.

The water dispersions of modifying resins and the colloidal silica solsmay be added as described under V, above.

The invention will be better understood by reference to the followingillustrative examples.

Example 1 This is an example of an aqueous dispersion containing anester type wax and colloidal silica, prepared according to Method I. Anaqueous dispersion of wax containing colloidal silica suitable for useas a self-polishing floor wax is made up with the following componentsin the indicated proportions by weight:

Percent by Parts by Weight Welght of Total Oarnauba. wax (No. 2 N. C.)40.0 13.64 Triethanolamine 4. 0 1. 36 Oleic Acid 8. 0 2. 73 Potassiumhydroxide KOH) 0.5 0. 17 er 200.0 76. 50 Colloidal Silica, 40% aqueoussolution 40.0 5. 46

i (as SiOa) The composition may be applied as a thin coating to alinoleum floor and is found to dry to a lustrous coating withoutrubbing. The coating is found to be remarkably Example 2 Parent;Emulsion of Wax plus Wax- Soluble Resin Component Modification of ParentEmulsion Parts by Weight #3 North Country Refined 33 Carnauba; Crown 36ooroscow oq 1 Final emulsion good after 5 weeks at 52 0.

RESULTS By the tests described above under Characterizations," films ofthe silica-modified emulsion on battleship linoleum had a gloss of 12, adynamic coefiicient of friction of .36, and a water-resistance of G,both before and after bufimg.

Example 3 Parent Wax Emulsion Parts by Component Weight.

#2 Yellow Carnauba 100 Oleic Acid 16. 9 Morpholine 1 13.20 28% Ammonia'8; 3

Modification of Parent Emulsion Colloidal SilicaSol Used-40% sol oi thetype characterized incolumns 10'and 11 (diluted to 12% solids). Waterdispersible Resin Used-Manila Loba C. Solids'Weight Ratio- ParentEmulsionzWater Dispersible Re'sinzColloidalSilica 80 50 Finallernulsiongood after 3 weeks at 52 C. and after 3 Ireeze thaw cyc es. MethodUsedfor Preparing Final Emulsion-V.

RESULTS Other Properties of Films Usual Properties oi Film on.Battleship Linoleum On Black Rubber Tile On Black Glass Gloss H2O WetRemov After-3 Gloss U 2 Resist- Leveling Gloss Leveling Abrasion abflitGloss Freezeance 3 'Resi stance y Thaw Cycles 16 0. 40 FG G 49 VG 3. 590 89 75 Example 4 Parent Wax Emulsion Modification of Parent EmulsionComponent #3 North Country Refined Colloidal Silica Sol Used% sol of thetype characterizedin columns Carnauba. 10 and 11 (diluted to 12%solids). Durez 219 30 Water dispersible Resin Used-Manila Loba C. Cardis319 s 30 Solids Weight Ratio- Melton Y-20- 10 Parent EmulsionzWaterDispersible Resin: Colloidal Silica Oleie Acid 14 2 50 Morpholine... 9Final emulsion good after 3 weeks at 52 C. and 3 freeze-thaw cycles 28%Ammonia. 5 Method Used for Preparing Final Emulsion-VI.

RESULTS Other Properties of Films Usual Properties of Film on BattleshipLinoleum On Black Rubber Tile On Black Glass Gloss H2O Wet Rem0v 'Afte!3 Gloss U 2 Resist- Leveling Gloss Leveling Abrasion abmt GlossFreezeance 3 Resistance y Thaw Cycles 12 52 FG G 31 E 2. 0 90 91 84 1Silica containing 10% morpholine based on S102. 1 Dynamic coeflicient offriction. a First rating is before buffing, second rating after bufiing.

Example 5 Parent Emulsion of War: plus" Wax Soluble Resin Modificationof Parent Emulsion Parts by Component Weight Cal-dis 319 ColloidalSilica Sol Used-40% sol of the typecharacterizedincolumns 30 10 and 11(Diluted to 12% solids). 1% Water Dispersible Resin Used2 ManilalLobaC:Shelite No. 1694 Solids Weight Ratio- Parent %mulsion:WaterDisnligrsible ResinzColloiial Silica Final emulsion good after 2 weeksat 52 0. Method Used for Preparing Final Emulsion-VI.

RESULTS Properties of Film on Black Rubber Tile Gloss Leveling Example 6Parent Wax Emulsion Modification of Parent Emulsion Component ggg fl #3North Country Refined Colloidal Silica Sol Used-40% sol of the typedescribed in Rule Carnaube 100 U. S. Appln. Ser. No. 183,902 (Diluted to12% solids). Oleic Acid- 16 Water Disperslble Resin Used-Shellae.Triethanolamme 12 Solids Weight Ratio- Ammonia 5 Parent fimulsion WaterDispg'sible Resin Colloirifal Silica Method Used for Preparing FinalEmulsion-VI. pH of Final Emulsion-7.36 Gloss of Final Film on BlackGlass-82 1 Shellac dispersed with Borax.

Example 7 Parent Wax Emulsion Modification of Parent Emulsion Componentaggga #3 North Country Refined Colloidal Silica Sol Used-% sol of thetype described in Rule Carnaubm 100 U. S. Appln. Ser. No. 183,902(Diluted to 12% solids). Oleic Acid... 16 Water Dispersible ResinUsed-Shellac 1 Triethanolamine. 12 Solids Weight Ratio Ammonia 5 ParentEmulsion :Water Dispersible Resin Colloids? Silica Method Used forPreparing Final Emulsion-VI. pH of Final Emulsion-8.46.

RESULTS Properties of Final Film On Black Glass On Black Rubber TileClarity Gloss Leveling Gloss 1 Shellac dispersed with ammonia.

( g 30) x 10- mho/cm.

where R is the silicazalkali metal oxide mole ratio, and containingamorphous silica in the form of dense, nonagglomerated, sphericalparticles having an average particle diameter of 10 to 130 millimicrons.

2. In a process for the preparation of a wax emulsion polishingcomposition, the steps comprising melting a wax, adding thereto anaqueous silica sol, then emulsifying the wax in the presence of thesilica sol to make a wax emulsion, the silica sol having a silicazalkalimetal oxide mol ratio of from 130:1 to 500:1, a relative viscosity offrom 1.15 to 1.55 as measured at 10% SiOz and pH 10, and a specificconductance, as measured at 10% SiOz and 28 C., of less than g 30) X 10-mho/em.

where R is the silicazalkali metal oxide mole ratio, and

containing amorphous silica in the form of dense, nonagglomerated,spherical particles having an average particle diameter of 10 to 130millimicrons.

References Cited in the file of this patent UNITED STATES PATENTS2,088,795 Kline Aug. 3, 1937 2,222,969 Kistler Nov. 26, 1940 2,577,485Rule Dec. 4, 1951 7 2,597,871 Iler May 27, 1952

1. A WAX EMULSION POLISHING COMPOSITION CONTAINING FROM 10 TO 50% OFSIO2, BASED UPON THE SOLID CONTENT OF THE WAX EMULSION, OF AN AQUEOUSSILICA SOL HAVING A SILICA: ALKALI METAL OXIDE MOLE RATIO OF FROM 130:1TO 500.1, A REACTIVE VISOCITY OF FROM 0.15 TO 1.55 AS MEASURED AT 10%SIO2 AND PH 10, AND A SPECIFIC CONDUCTANCE, AS MEASURED AT 10% SIO2 AND28* C., OF LESS THAN